This application relates to an ink jet cartridge or cassette as used in an ink jet printer, and more particularly to an apparatus for reducing the introduction of air into the system. It will be appreciated, however, that the invention may find application in related environments and applications that encounter these same issues.
It is generally known in the art to form a cartridge housing or body having one or more cavities or chambers that hold a predetermined supply of ink. For example, a single color of ink may be provided in a single chamber cartridge. Alternately, multiple chambers may be provided, for example, each holding a different color ink stored therein for selective use in a color printer. It is also generally known to provide an ink absorbing member such as a reticulated polyurethane, melamine, or polyethylene foam (a hydrophilic foam) that fits within the chamber. In some arrangements, the ink absorbing member fills the substantial entirety of the chamber, while in other instances a portion of the ink supply is free ink and the remainder is stored in the ink absorbing member. In still other arrangements, the cartridge contains only free ink. One or more outlet ports communicate with the respective one or more chambers through outlet passages. The outlet passage proceeds through a first or bottom wall of the housing. A supply needle from an associated printer extends through the outlet port and thus conveys ink from the housing to a recording head or printhead.
Print quality can be adversely effected by the introduction of air into the ink cartridge, for example, into the chamber or outlet passage. Thus, manufacturers of ink cartridges are careful in the design and assembly, i.e., filling, to limit the potential for air introduction into the system. One area of potential air introduction is an aperture of the outlet passage where the outlet passage communicates with the ink chamber. It has been determined that by breaking the surface tension of the ink, air bubbles will be prevented from migrating and thus undesirably forming larger air bubbles in the outlet passage. This is particularly a problem in the outlet passage below the base wall aperture and around the printer needle. Introduction of air interrupts the capillary flow from the chamber to the printhead. Since air can result in print quality problems such as voids or ink starvation, a need exists to improve print quality and particularly limit the potential for air migrating into the outlet passage as it proceeds from the ink chamber to the outlet port.
The present invention provides an ink cartridge having a housing with a chamber therein for storing ink. A first surface of the housing has an aperture that communicates between the chamber and an outlet passage. The aperture/outlet passage includes means for breaking surface tension of ink as the ink passes therethrough.
In an exemplary embodiment, the surface tension breaking means includes a serrated edge about a periphery of the aperture.
In another embodiment, the means for breaking surface tension includes a substantially cruciform divider disposed in the aperture.
In yet another embodiment, irregular shaped passages lead to the aperture.
The aperture may have a substantially constant cross-section throughout its length or a non-uniform cross-section. A tapering region decreasing in cross-sectional area as it proceeds from the cavity toward the outlet port also provides an alternate embodiment.
A primary advantage of the invention resides in the improved print quality that results.
Another advantage of the invention relates to preventing migration of air bubbles toward the print needle.
Still other advantages and benefits of the invention will become apparent to those skilled in the art upon reading and understanding the following detailed description. de
The invention may take form in certain components and structures, preferred embodiments of which will be illustrated in the accompanying drawings.
FIG. 1 is an exploded view of an ink jet cartridge.
FIG. 2 is a cross-sectional view of an assembled cartridge.
FIG. 3 is a plan view illustrating a first or bottom wall of the cartridge.
FIG. 4 is an enlarged view of the bottom wall of the cartridge.
FIG. 5 is a bottom plan view of the cartridge.
FIG. 6 through 30 are views of alternate embodiments.